D-FOUNDATIONS

CPT based foundation engineering

Bearing capacity versus depth for several pile types and CPT’s

In the 1930s, Deltares (formerly known as GeoDel� )

started the development of the Cone Penetration

Test (CPT). In twenty years time this has evolved

into the electrical cone, for which several national

and international patents were granted. CPT testing

is the standard soil test in The Netherlands, as it

is accurate, fast and cost e� cient. Since then it is

impossible to imagine soil investigations in so� soil

countries without the “Dutch Cone” test.

CPT tests measure cone resistance, as well as skin

friction along the friction sleeve near the cone.

These properties are ideal for the design of piled

foundations, where both pile base resistance and

pile sha� resistance are important.

Based on CPT test results, calculation techniques

and design codes have been developed for the

design of piled foundations in The Netherlands and

Belgium. Since 1990, Deltares has been involved in

the development of foundation design so� ware.

This has resulted in design and verifi cation

so� ware for bearing piles, tension piles and shallow

foundations. Previous releases of D-FOUNDATIONS

were called MFoundation.

General

D-FOUNDATIONS follows the Eurocode 7 and the Dutch and Belgium

National Annexes. First D-FOUNDATIONS is used to create and optimize

a design. In this process, automatic optimization options assist the

user to e� ciently create and fi ne-tune a design. Once the design is

fi nished D-FOUNDATIONS can perform a design code check resulting

in a detailed report for the given situation. The ability to overrule

and redefi ne various design code parameters allows D-FOUNDATIONS

to be used by engineers for specialized calculations using user

defi ned foundation types and factors. Some specifi c features in

D-FOUNDATIONS are:

• Soil data defi nition

D-FOUNDATIONS requires input data from Cone Penetration Tests

(CPT). Importing CPT data is possible in several formats, including

the Geotechnical Exchange Format (GEF) and the format used

by the Database Ondergrond Vlaanderen (DOV). Besides using

GEF-fi les, CPT’s can be imported directly from the Dutch DINO

database by TNO. The automatic CPT interpretation tool provides

soil-type dependent proposals, including design code based

parameter proposals.

• Preliminary design of piles

D-FOUNDATIONS provides simultaneous results of bearing capacity

and required length for di� erent pile types and di� erent soil

conditions.

• Pile group interaction

In calculations, the e� ect of pile group interaction on settlement

is included as well as on bearing capacity for the selected pile

type and pile plan.

• Design of shallow foundations

Foundation dimensions can be optimized. In addition, the required

width for strip foundations and the capacity and stability of

shallow foundations can be checked.

D-FOUNDATIONSCPT based foundation engineering

Bearing capacity versus depth for several pile types and CPT’s

Load settlement curve for bearing piles

The pile library window

• Code-based verifi cation

A complete verifi cation report can be generated in Dutch and

English.

• Standard parameters

All standard parameters provided by Eurocode 7 (such as soil

parameters and pile type parameters) are incorporated within

D-FOUNDATIONS for easy and fast selection.

D-FOUNDATIONS comes as a standard module (Bearing piles), which

can be extended further with other modules to fi t other applications:

• D-FOUNDATIONS Standard module (Bearing piles EC7-NL)

• Shallow Foundations module (EC7-NL)

• Tension Piles module (EC7-NL)

• Bearing Piles module (EC7-B)

• Feasibility module.

Standard module (Bearing piles EC7-NL)

The standard module is intended for the design and verifi cation of

bearing piles. In short terms it allows for the input of projects, the

analysis, and it provides tabulated and graphical output of results

both on-screen and in a report. The output is available in Dutch

and English. The bearing piles module is used to fi rst determine

the bearing capacity with depth for a number of preferred piles.

Once the bearing capacity is determined, the user can choose the

most appropriate pile. A� er the preliminary design, the entire pile

plan is entered and can be checked according to the design code.

The result of this verifi cation will show if the design is according

to the standard and will also provide the user with the calculated

settlements. The program provides fast options for re-calculation,

using di� erent pile types and fi ne-tuning of the pile plan. In this

manner a cost e� cient design can easily be obtained. Some specifi c

features of the standard module include:

CPT interpretation

The automatic CPT interpretation uses the relation between cone

resistance and skin friction using standard interpretation rules

such as the well-known Robinson (CUR) rule. The user can specify

the layer thickness to be distinguished. A� er the interpretation the

proposed soil profi le can be edited by the user. I.e. layers can be

changed, added, removed or changed in thickness graphically.

If desired, users can specify their own interpretation rule by

specifying the relation between the cone resistance and skin

friction. For each rule, the user can specify the soil types to be

recognized. One can use the soil type preset by D-FOUNDATIONS,

according to the table of standard soil types as specifi ed in the

Eurocode 7, or specify their own soil types table.

Pile library

A pile library containing most standard piles provides the default

parameters according to the design code. This includes αp, the pile

factor for the pile point and αs, the pile factor for sha� friction, the

pile sti� ness and the pile adhesion. Users can also specify their

own pile types and properties.

CPT interpretation window

Results are presented on-screen and as printed reports

Loading input for shallow foundations

Generated pile group a� er using pile grid generator

Tree view

The pile library window

Pile grid generator

The pile grid generator eases the input of complex pile plans for

equally spaced as well as non structured pile groups.

Tree view

D-FOUNDATIONS uses a tree view that contains all menu-items

relevant to a design/verifi cation calculation. The user can navigate

through these items manually, or use a wizard that fi lls in the

required input for a standard pile design calculation.

Shallow Foundations module (EC7-NL)

This module allows for the design of strip footings, as well as square

or circular footings. The verifi cation is based on the Eurocode

7 design code for shallow foundations, and the Dutch National

Annex. The Shallow foundations module takes into account:

• horizontal and vertical loads

• load spread

• eccentricity of loads

• interaction between footings

• automatic optimization of foundation size for given loads

• maximum bearing capacity for a given foundation

• verifi cation of the foundation according to design code

• check on punch through for foundations on non-cohesive layers

located above a cohesive layer

• check on tip-over stability

• check on bearing capacity if a slope is nearby

• check on squeezing e� ects.

Tension Piles module (EC7-NL)

For some constructions a foundation capable of dealing with upli�

forces is needed. A foundation on tension piles may o� er a more

economical alternative to constructions that counter the upli�

forces by ballast. The tension pile module is used to determine

the pile length needed according to the Eurocode 7. D-FOUNDATIONS

determines the tensile capacity and required length for each pile in

a user defi ned pile group for di� erent pile types and selected CPT’s.

The Tension Piles module takes into account:

• reduction of cone resistance due to excavation

• safety factors for design

• e� ects of pile installation

• reduction of stresses due to tension forces in pile groups

• pile weight and weight of soil body being pulled.

Project Properties Description Construction Sequence

Soil Materials Profi les 1 2

Foundation Pile Types Rect 400x400 Rect 500x500 Pile Properties Top View Foundation Excavation Calculation

Results Load-Settlement Curve Design Intermediate Report

Bearing Piles module (EC7-B)

This module is similar to the base module of D-FOUNDATIONS for

bearing piles, however, in this case the Belgium National Annex of

the Eurocode 7 has been used. The Belgium Annex for bearing piles

supports all three models available in D-FOUNDATIONS:

• method “de Beer”

• method “Van Impe/de Beer”

• method NEN.

The bearing capacity for the pile tip, qb, is calculated with one of

the three above methods. D-FOUNDATIONS also supports rules that

incorporate sha� bearing capacity, qs. Finally, the construction

design value Rcd, is calculated, incorporating the safety philosophy

of the Eurocode 7.

The Bearing piles module for the Belgian method supports the

input of mechanical CPT’s, electric CPT’s and CPT’s that can be

downloaded free of charge from the DOV (Databank Ondergrond

Vlaanderen).

Feasibility module

During the design of a piled foundation, the foundation is checked

according to guidelines like the Eurocode. In practice, this does

not guarantee that the project is feasible. This may depend on

many other local factors, among which the equipment used

during construction. For this purpose, the use of the Feasibility

module helps the user to evaluate the feasibility of their project by

comparison with experiences.

GeoBrain Foundation technics experiences

In 2002, GeoDel� started a project called GeoBrain which aim was

to develop a prediction model for the feasibility of foundation

works. Hundreds of project experiences concerning the driving of

sheet pile walls and piles were therefore received for study. The

Feasibility module provides access to these experiences. These

may help the users to predict the feasibility of their projects.

GeoBrain Foundation technics predictions

The designed piles can also be checked using the GeoBrain

prediction model. D-FOUNDATIONS will transfer the information over

the internet to the GeoBrain predictions model. Results of GeoBrain

are represented and pre-cautions for improvement are suggested.

Interaction with other Deltares systems tools

D-FOUNDATIONS requires the input of digitized CPT’s which are now

widely available. In some situations CPT’s only exist on paper.

The GEFPlotTool by Deltares is available for digitizing of electric

and mechanical CPT’s and to convert them to the Geotechnical

Exchange Format (GEF) standard. For a full 3D analysis of piles

and pile groups including pile interaction under vertical as well

as horizontal loading, Deltares systems provides the D-PILE GROUP

program. D-PILE GROUP follows the American Petroleum Institute

(API) standard. Please refer to the D-PILE GROUP page for additional

information.

Support

Deltares systems tools are supported by Deltares. A group of

70 people in so� ware development ensures continuous research

and development. Support is provided by the developers and if

necessary by the appropriate Deltares experts. These experts can

provide consultancy backup as well.

On-line so� ware (Citrix)

Besides purchased so� ware, Deltares systems tools are available

as an on-line service. The input can be created over the internet.

Heavy duty calculation servers at Deltares guarantee quick

analysis, while results are presented on-line. Users can view and

print results as well as locally store project fi les. Once connected,

clients will be charged by the hour.

D-FOUNDATIONS Feasibility module

PO Box 1772600 MH Del� Rotterdamseweg 1852629 HD Del� The Netherlands

T +31 (0)88 335 79 09F +31 (0)88 335 81 11

info@deltaressystems.comwww.deltaressystems.com

Photo’s by: BeeldbankVenW.nl, Rijkswaterstaat.